Combination fluid flow speed and direction transducer

ABSTRACT

A transducer including an anemometer having a magnetic flux concentrator in one arm thereof and including an earth&#39;&#39;s magnetic field sensitive device for providing a first electric signal which is a measure of both wind direction and the direction of the earth&#39;&#39;s magnetic field. A permanent magnet fixed to the rotating anemometer energizes once each revolution thereof a reed switch positioned by a wind vane, thereby producing another electric signal which corresponds to the wind direction. Both signals are applied to an indicator which provides a simultaneous indication of wind speed and wind direction relative to the earth&#39;&#39;s magnetic north pole.

[ 1 Jan. 30, 1973 Arthur E. Korkosz Sughrue, Rothwell, Mion, Zinn &Macpeak ABSTRACT 6 Claims, 14 Drawing Figures Primary Examiner-RichardC. Queisser Assistant Examiner- Altomev A transducer including ananemometer having a magnetic flux concentrator in one arm thereof andincluding an earths magnetic field sensitive device for providing afirst electric signal which is a measure of both wind direction and thedirection of the earths magnetic field. A permanent magnet fixed to therotating anemometer energizes once each revolution thereof a reed switchpositioned by a wind vane, thereby producing another electric signalwhich corresponds to the wind direction. Both signals are applied to anindicator which provides a simultaneous indication of wind speed andwind direction relative to the earth's magnetic north pole.

Joseph Madis- .G0lw 1/02 I i i .i ii Hutu lullllllllllillllllll l hllv.\ Go f. ..g! ;vl. n$it Ii United States Patent Bernstein et al.

COMBINATION FLUID FLOW SPEED AND DIRECTION TRANSDUCER Inventors:Theodore Bernstein, 5105 Regent Street, Madison, Wis. 53705; G. Miller,2113 Tauhee Dr on, Wis. 53711 22 Filed: Nov. 27, 1970 211 Appl. No.:93,371

[52] U.S.Cl........................................73/l89,33/204 [51][58] Field of Search ..............73/189; 33/204; 324/47 INVENTORSTHEME BERNSTEIN MP" 6. IILLER Sk /tr M Z m I Miptc K ATTORNEYS 4PATENTEDJAN30 nan sum 1 UP 4 v PATENTED JAN 30 I973 SHEET 2 OF 4 72COUNTER l TRANSDUCER OUTPUT no. a

PATENTEDJAIBO I978 3,713,336

sum 3 BF 4 AIR GAP" AIR EXIT I N -42, FLUX HOLLHQ ROWING 1 CONCENTRATORHOUSING 3a, MAGNETO- I20, TRERmsmR 30/ wmn BEARING"-* I n4, OPENING AIREj GROM'QZ ROLEfI'JP :27

TRANSISTOR BEARING DIRECTION 0F 4 BASE ROTATION, I26

THERMISTOR LEADS MITATIVE THERMISTOR RESISTANCE vARlAnow }LEADS FOR RTPRIMARY EXCITATION cuP CONTAINING THERMISTOR MOVES INTOWIND TIMECOMBINATION FLUID FLOW SPEED AND DIRECTION TRANSDUCER BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates generally tothe field of devices for indicating the azimuth of the earths magneticpoles and also for indicating the speed and direction of this fluidflow, and, more particularly, to a transducer which simultaneouslyproduces electric signals indicative of both the speed and/or magneticazimuth of a fluid flow, such as wind.

2. SUMMARY OF THE INVENTION The broad object of this invention is toprovide an improved combination fluid flow speed and directiontransducer.

In one preferred embodiment, this object is accomplished by mounting ananemometer housing on a wind vane which points in the direction of thewind. A magnetic switch is mounted to move with the wind vane. Amagnetic flux concentrating rod is mounted in the arm of one of theanemometer wind cups and forms a part of a magnetic circuit. Positionedin the magnetic circuit is a magnetic field responsive electric device,such as a magnetodiode, which has an electrical characteristic whichchanges in response to the magnitude and polarity of the magnetic fieldto which it is exposed. The magnetic field responsive device isconnected in an electric circuit which produces a signal proportional toboth the magnitude and direction of the earths magnetic field and alsoto the speed of rotation of the anemometer. Furthermore, the magneticswitch is activated to produce another electric signal each time apermanent magnet fixed to the rotating anemometer shaft passes theswitch, thereby providing an indication of wind direction. The twosignals are then applied to an indicator which indicates both the windspeed and the wind direction or azimuth relative to magnetic north.

In other preferred embodiments of the invention, the wind vane andmagnetic switch are replaced by either a pressure sensitive transistoror by a self-heating thermistor. In variations of these embodiments,when the azimuth of the earths magnetic north pole is known, themagnetic circuit is not required, and other means are employed toproduce the signal indicative of the direction of the magnetic northpole.

In still another embodiment, the anemometer and wind direction sensingmeans are eliminated and the flux concentrating rod is mounted on amoving object and driven by a motor to provide an electronic compasswhich indicates the direction in which the object is heading. v

Hence, another object of the invention is to provide an improvedcompass.

These and other objects will become apparent from the followingdescription and illustrations of preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional perspective viewof one embodiment of the invention.

FIG. 2 is a schematic diagram of an electric circuit which may be usedin conjunction with the transducer illustrated in FIG. 1.

FIG. 3 illustrates the signal wave forms produced by the transducer ofFIG. 1 and the circuit of FIG. 2.

FIG. 4 is a schematic diagram of the structure of a magnetodiode.

FIG. 5 is a graph illustrating the current-voltage characteristic of amagnetodiode for different magnetic fields.

FIG. 6 is a sectional perspective view of another embodiment of theinvention.

FIG. 7 is a schematic diagram of a circuit which may be used inconjunction with the embodiment of FIG. 6.

FIG. 8 is a graph illustrating signal wave forms produced by thetransducer illustrated in FIG. 6.

FIG. 9 is a schematic top view of another embodiment of the transducerof this invention.

FIG. 10 is a front schematic view of the embodiment of FIG. 9.

FIG. 11 is a graph illustrating a signal waveform produced by theembodiment illustrated in FIGS. 9 and 10.

FIG. 12 is a schematic diagram of a circuit which may be used inconjunction with the transducer illustrated in FIGS. 9 and 10.

FIG. 13 is a graph illustrating various signal wave forms produced bythe circuit of FIG. 12.

FIG. 14 is a schematic diagram of the electronic compass embodiment ofthe invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the preferred embodimentillustrated in FIG. 1, the combination fluid flow speed and directiontrans ducer is depicted as a wind speed and direction transducer I0.Transducer l0 basically comprises an anemometer 12 mounted on a base 14which in turn is fixed to a wind vane assembly 16. The wind vaneassembly I6 is rotatably mounted on a support 19 which in turn may befixed, for example, to the cable of a weather balloon or the top of abuoy.

The anemometer 12 consists of a hollow cylindrical housing 18 havingthree holes 20a, b, c, for receiving and retaining three correspondingtubular'wind cup arms 22a, b, c, to the opposite ends of which are fixedthe anemometer wind cups 24a, b, 0, respectively.

The anemometer housing 18 is rotatably supported by bearings 26 and 28on the tubular member 30 of the base 14 of the transducer. Tubularmember 30 extends upwardly within housing 18 and has a vertical axiswhich is co-axial with the axis of rotation of the anemometer housing18. The base 14 is fixed to the wind vane assembly 16 by suitable means,such as bolts 32 and 34. 7

Fixed to the top of the tubular member 30 is a high permeabilitymagnetic pole shoe 36. Fixed to the bottom of shoe 36 is amagnetoelectric transducer, such as a magnetodiode 38, and fixed to thelower surface of the magnetodiode is an L-shaped high permeabilitymagnetic flux collector 40. Leads 39 and 41 are connected to themagnetodiode 40. The magnetoelectric transducer may also be amagneto-sensitive resistor, Hall'effect device, etc. The hollow interiorof tube 30 is filled with epoxy to bind the components in place.

Disposed in only one of the tubular arms 22, such as arm 22a, is a highpermeability magnetic flux concentrating rod 42 which concentrates andsteers the earth7s magnetic flux, or field to which it is exposedthrough the magnetic circuit including the magnetic pole shoe 36, themagnetodiode 38 and the L-shaped flux collector 40. Additional rods ofnon-magnetic material, such as stainless steel, are placed in arms 22band 22c to balance the anemometer. There is an air gap between the topsurface of shoe 36 and the inner end of rod 42.

Also fixed to the tubular portion 30 of the base 14 is a magnetic reedswitch 44 having a pair of electrical leads 46 and 48. Reed switch 44 ispositioned over the wind vane 50 of the wind vane assembly 16, i.e. ispositioned in the plane defined by the longitudinal axis of the vane 50and the axis rotation of the anemometer 12. Since base 14 is fixed tothe wind vane assembly 16, the angular position of reed switch 44 isalways identical to that of the arrowhead of wind vane 50 which pointsin the direction from which the wind is blowing.

Fixed to the anemometer housing 18 at the same height as reed switch 44is a permanent magnet 52, which functions to activate the reed switch 44when it is opposite the switch. Since the anemometer 18 rotates relativeto the base 14 in accordance with the speed of the wind to which theanemometer cups are exposed, permanent magnet 52 passes over reed switch44 once each revolution of the anemometer, thereby activating the reedswitch once each revolution.

Even though a reed switch and permanent magnet are disclosed in thispreferred embodiment, it is to be understood that other proximityswitching means, such as a photocell and light source, magnetic fluxdependent resistor and magnet, mechanical switch and actuator, etc. maybe used.

The operation of the transducer illustrated in FIG. 1 will be describedin reference to that figure and also by reference to the schematiccircuit diagram illustrated in FIG. 2 and the signal wave formsillustrated in FIG. 3.

The magnetic field sensitive magnetodiode 38 illustrating FIG. 1actually comprises a pair of magnetodiodes 60 and 62, mounted physicallyback to back and electrically connected in series as shown in FIG. 2.These magnetodiodes are manufactured by Sony Corporation of Tokyo,Japan. Basically, a magnetodiode is a magneto-sensitive semiconductordevice which works on the principle of controlled lifetime of injectedcarriers by an external magnetic field. Even though a singlemagnetodiode may be used to sense the earths magnetic field, theback-to-back arrangement shown in FIG. 2 is insensitive to temperaturevariations. When a constant battery voltage E is applied across themagnetodiodes 60 and 62 as illustrated, the center potential V,,.without any applied magnetic field is substantially E/2 at anytemperature. In this arrangement, for a given magnetic field direction,the resistance of one of the magnetodiodes will increase while that ofthe other will decrease. The incremental change of V with an appliedmagnetic field of lkOe is typically 1.5 volts for an E of 9 volts. Thewave form of V, is illustrated in FIG. 3a.

The structure of a magnetodiode is schematically illustrated in FIG. 4.There, a magnetodiode 60 or 62 is shown to be a PIN semiconductor devicewherein the region i is a rectangular strip-shaped body of substantiallyintrinsic semiconductor in which the carrier concentration is low andcan be efficiently modulated by injection. The regions p+ and n+ containhigh concentrations of acceptors and donors, respectively, to facilitateefficient double injection of holes and electrons into the i-region. Thedistance between the p+ and n+ regions is made several times larger thanthe ambipolar diffusion length. The zone r is formed locally either bymechanical means at the surface or by diffusion of certain impuritiesinto the bulk of the i-region, so that the recombination ofnon-equilibrium electrons and holes takes place much more rapidly herethan in the remainder of the i-region.

FIG. 5 is a graph illustrating the current-voltage characteristic of amagnetodiode for a magnetic field H O, and for the magnetic field PH andthe magnetic field I-I- having the relative polarities as indicated bythe corresponding arrows in FIG. 4.

In operation, the wind cups 240, b, and c of the anemometer 12 arepositioned such that the anemometer always rotates in a given direction,for example, clockwise when viewed from the top. For this direction ofrotation then, the flux concentrating rod 42 directs through themagnetic circuit, including the rod 42, pole shoe 36, magnetodiodes 38,and flux collector 40, a magnetic field whose magnitude variessinusoidally in time, with each cycle of the sinusoid corresponding to 1complete revolution of the anemometer. The voltage V follows themagnetic field variation to produce the wave form V,, illustrated inFIG. 3a. This voltage is applied through a DC blocking capacitor 64 andan amplifier 66 to one input terminal of an indicator, which isillustrated in this example as a two-channel oscilloscope 70. Thedisplay of the sinusoidal wave form V is illustrated in FIG. 3a.

The back-to-back magnetodiodes 60 and 62 are oriented such that, whenthe concentrating rod 42 is pointing towards the earth's magnetic northpole, the wave form V,,, is at its most positive level. In this case,the resistance of magnetodiode 60 is less than the resistance ofmagnetodiode 62. As the flux concentrating rod 42 rotates clockwise, Vdecreases till it reaches 0 for the Due East direction E. Similarly,when the rod is pointing, Due South S, V,, is at most negative level.The speed of rotation of the anemometer and thereby the wind speed canbe calculated by properly calibrating the face of the oscilloscope inrevolutions per second or units of wind speed. Alternatively, a cyclecounter 72 calibrated in wind speed can be connected to the output ofamplifier 66.

As the anemometer rotates at a speed proportional to the wind speed, thepermanent magnet 52 passes over the reed switch 44 once each revolution.As shown on FIG. 2, switch 44 is connected in series with a DC source E,and a current limiting resistor 74. Each time the switch 44 is closed bythe rotating magnet 52,

the circuit is closed between resistor 74 and source E to provide avoltage pulse on conductor 76 connected to the other input terminal 78of the dual channel oscilloscope 70. The pulses 80 produced by theclosures of switch 44 are illustrated in FIG. 3b. Since the wave formsof both V,, and pulse 80 are presented simultaneously on the face of thescope, the position or phase of pulse 80 relative to the wave form V, iseasily determined, and thereby the magnetic direction or azimuth of thewind is easily determined. It will be recalled that the magnetic reedswitch 44 is fixed to the base 14 so that the angular position of theswitch is identical to that of the arrowhead of the vane 50 which pointsinto the wind. Consequently, the wave forms presented in FIGS. 3a and 3bindicate that the compass or magnetic direction of the wind isEast-by-Northeast. By knowing the time base of the oscilloscope, thecycle length of this sinusoidal wave displayed in FIG. 30 represents thewind speed. Of course, as previously mentioned, the signal V may beapplied to separate cycle counter 72 calibrated directly in units ofwind speed. It is of course obvious to one skilled in the art that theoutputs of the magnetodiode and the reed switch may be electricallycombined to provide a single trace on scope 70 of illustrated in FIG.30.

The leads of magnetodiodes 38 and of reed switch 44 are connected tobrushes 71 fixed to base 14. The brushes ride on slip rings 73 which arefixed to support 19 and provide means for applying the signals to scope70. Alternatively, a power supply and radio transmitter could be mountedon assembly 16 and connected to the leads of the magnetodiodes and reedswitch, thereby eliminating the need for the brush and slip ringassembly.

FIG. 6 illustrates an embodiment of the invention which does not requirethe wind vane assembly 16 of FIG. 1. Corresponding parts of FIGS. 1 and6 carry the same reference numerals. In this embodiment a hole 90 isbored in the rotating anemometer housing 18, and a circular groove 92 iscut in the tube portion 30 of the base 14 at the same height as the hole90. A vertical groove 94 is also formed in tube 30 in communication withthe circular groove 92. A pressure-sensitive electric transducer, suchas a pressure-sensitive diaphragmoperated transistor 96, is mounted inthe groove 94. The upper part of the transducer including the fluxconcentrating rod 42, the magnetic field responsive transducer 38, andmagnetic circuit elements 36 and 40 are the same as in the FIG. 1embodiment.

In operation, as the anemometer is rotated by the wind, the air hole 90and housing 18 rotate about the groove 92 to permit wind to pass throughthe hole 90 into the grooves 92 and 94 and to the pressure sensitivetransducer 96 which produces an electrical output corresponding to thewind pressure impinging upon the transducer. Consequently, once eachrevolution of the anemometer, the pressure transducer 96 will experiencemaximum wind pressure and produce a corresponding maximum signal.

FIG. 7 is a schematic diagram of a circuit including the pressuresensitive transistor 96. Pressure sensitive transistor 96 has apressure-responsive diaphragm 98, and the voltage V is a sinusoidalsignal whose phase depends upon the wind direction. For example when thehole 90 is facing into the wind, the maximum wind pressure is seen bythe transistor 96 and produces maximum levels of voltage wave form V,,.As the anemome' ter continues to rotate, the pressure seen by thetransistor reduces until it is at a minimum value when the hole 90 is180 from the wind direction. The signal V, is applied through a DCblocking capacitor 100 and an amplifier 102 to one input terminal 104 ofa twochannel oscilloscope 106. In like manner, the earths magnetic fieldsignal V,,, is applied to the other input terminal 108 of theoscilloscope.

FIG. 8 illustrates the wave forms V and V displayed on the oscilloscope.Once again, the maximum positive polarity of V, indicates the directionof the earths magnetic north pole, and here the phase of V,

relative to V,, indicates the wind direction relative to magnetic north.In the case illustrated, the maximum voltage peaks of V, indicate thatthe wind direction is again East-by-Northeast.

In the embodiment of the invention illustrated in FIGS. 9, 10 and 12,the pressure sensitive transistor 96 is replaced by a self-heatingthermistor for sensing the wind direction.

In this embodiment, a self-heating thermistor is placed in a channel inthe rear of one of the anemometer wind cups so that when the back ofthis wind cup is facing in the direction of the wind, the thermistor iscooled, thereby changing its resistance. The change of resistance iselectrically detected to produce a signal which is an indication of thewind direction. The magnetic field direction detecting part of thetransducer is the same as that illustrated in FIGS. 1 and 6. Thethermistor-derived signal and the magnetodiode signal are then appliedto an indicator, such as an oscilloscope, so that the speed and magneticdirection of the wind may be determined.

As shown in a schematic top view in FIG. 9, the anemometer cup 1 10 ismodified to include a T-shaped tube 112 having an open end 114 at theback of the cup. Air holes 116 and 118 are formed in the T-shaped tube112 at the front of the cup. A self-heating bead thermistor 120 ismounted in the T-shaped tube as illustrated. A pair of electrical leads122 and 124 connect the thermistor to a rotating transformer which isillustrated in more detail in FIG. 10. Again, assuming the anemometercups are rotating in a clockwise direction indicated by arrow 126, thethermistor experiences maximum cooling when the back of the cup isfacing directly into the wind indicated by arrows 127. At this time, thethermistor has its highest resistance, and this condition is detected asis being described in more detail in connection with FIGS. 10 13.

As shown in FIG. 10, the thermistor is energized by means of a rotatingtransformer 126 including a secondary winding 128 electrically connectedto the thermistor leads 122 and 124 and wound on the rotating anemometerhousing 130. The transformer also includes a primary winding 132 whichis fixed to the stationary base 134 of the transducer. Leads 136 and 138are connected to a suitable AC source.

In operation, the AC power applied to the primary winding 132 induces avoltage in the secondary winding 128 to heat the thermistor 120 abovethe ambient temperature. When the rear of the anemometer cup 1 10 isfacing directly into the wind, the resulting cooling of the thermistorproduces an increase in the resistance of the thermistor, and thisincrease in the resistance of the secondary circuit of the transformeris reflected into the primary circuit and detected as a current pulseindicative of the wind direction. This current pulse is applied alongwith the voltage V,,, from the magnetodiode sensing circuit 140 to asuitable indicator, such as an oscilloscope, as illustrated in theprevious embodiment.

FIG. 11 is a graph illustrating the thermistor resistance R versus timeas the anemometer rotates in the wind. The peaks 142 and 144 correspondto the points in time when the rear of the anemometer cup is facingdirectly into the wind. For the thermistor actually used, a differenceof a resistance of- AR= 200 ohms was noted as the difference between thepeak resistance and the minimum resistance of the thermistor.

FIG. 12 is a schematic block. diagram of a thermistor energizing andwind direction sensing circuit which may be used in conjunction with thetransducer of FIG. 10.

A 200 kHz Colpitts sine wave oscillator drives the primary winding 132of the rotating transformer 126. The secondary winding 128 is attachedmechanically to the rotating housing 130 of the anemometer and isconnected electrically across leads 122 and 124 of thermistor 120. Thecooling action of the thermistor is sensed by a sensing resistor 150connected in the primary circuit. As the wind cools the thermistor andraises its resistance, the decrease in current in the secondary windingis reflected as a corresponding decrease in the current in the primarywinding. Thus, the voltage across the sensing resistor 150 is a 200 kHzsine wave which is amplitude modulated by the wind direction signal asshown in FIG. 13a. The voltage across the sensing resistor 150 is thenpassed through a demodulator and smoother 160 and a low pass filter andamplifier 160 to extract the wind direction signal 165 illustrated inFIG. 13b. Wave form 160 is converted to pulses of constant amplitude andconstant width by means of an adaptive thresholding circuit 166 whichincludes a peak holding circuit and a comparator. The output of circuit166 is shown as wave form 168 in FIG. 130. The pulse train 168 isapplied to the input of a monostable flip-flop (MSFF) 170, whichproduces a train of pulses of 4 volt amplitude and millisecondsduration. The output of MSFF 170 is shown in FIG. 13d and may be appliedto an oscilloscope along with the voltage signal V from the magnetodiodecircuit 140 or else may be applied to other suitable telemetrycircuitry.

In the embodiments of the invention described up to this point, it hasbeen assumed that the direction of the magnetic north pole of the earthwas unknown. This condition occurswhen the transducer is mounted on acable of a tethered balloon or on the top of a water buoy or on otherapplications when it is impossible to fix the position of the transducerrelative to the earths surface and thereby to the earths magnetic pole.However, in many installations the base of the transducer may bestationary with respect to the earth, and therefore the direction of themagnetic north pole is known. In these types of installations, theembodiments illustrated in FIGS. 6 and 10 may be modified since it isnot necessary to actually detect the direction of the earth's magneticfield. In such cases, the magnetic field sensitive device, such as themagnetodiode is not required, and only the wind direction sensing partof the transducer is needed.

Consequently, in the FIG. 6 embodiment for example, the fluxconcentrating rod 42, the pole shoe 36, the magnetodiode 38, and theflux concentrator 40 may be eliminated. For the permanent installationdescribed, the base 14 is fixed relative to the earth. A magnetic reedswitch is positioned on the fixed tubular portion so that it faces theearth's magnetic north pole. A permanent magnet is then fixed to therotating anemometer housing 18 so that it passes over and ac-v tivatesthe reed switch once each revolution of the anemometer. Consequently, inorder to determine the magnetic azimuth of the wind. direction, it isonly necessary to compare the phase of the maximum values of the outputwave form from the pressure transducer 96 with the switching pulsesproduced at each closure of the magnetic switch.

In like manner, the embodiment of FIG. 10 may be modified for fixedinstallations by eliminating the magnetodiode and associated magneticelements 140, and again fixing a reed switch to base 134 so that theswitch always faces the magnetic north pole. Again, a permanent magnetis fixed to the rotating housing 130, so that a switch pulse is producedonce each revolution of the anemometer corresponding to the azimuth ofthe magnetic north pole. The output of the thermistor is then comparedwith the switching pulses to determine the magnetic azimuth of the winddirection in the same manner as described for the fixed installationmodification of the FIG. 6 embodiment employing the pressure sensitivetransistor.

Another embodiment of the invention involves a variation of theembodiment illustrated in FIG. 1. In this figure, the magnetic circuitincluding the flux concentrating arm 42, the pole shoe 36, themagnetodiode 38, and the flux concentrator 40, in combination with theassociated indicator, may be considered as an electronic compass sincethe signal V, represents the direction of the earths magnetic field asthe anemometer rotates through 360. The positive peaks of this signalrepresent the magnetic north pole for clockwise rotation of theanemometer.

In the variation illustrated in FIG. 14, only the electronic compassportion of the embodiment of FIG. 1 is utilized, and the anemometer isreplaced by an electric motor (M) 180 which rotates the housing 182around a vertical axis 184 by means of a ring and pinion gear assembly186 or other similar device. The housing 182 is rotatably mounted on thebase member 186 by means of a suitable bearing 188. A horizontalmagnetic rod 190 extends radially from the housing 182 and serves toconcentrate the earths magnetic field as already explained in connectionwith FIG. 1. The flux from rod 190 is directed to a magnetic circuit 192consisting of a magnetodiode and associated magnetic elements asillustrated in FIG. 1. As the motor continuously rotates housing 182 androd 190, the magnetic circuit 192 will generate the voltage V asillustrated in FIG. 3a.

A magnetic reed switch 194 is fixed to base 186 and oriented so that isalways faces the front of a vehicle 196 to which the base 186 is fixed.A permanent magnet 198 is mounted on the rotating housing 182 so that itpasses over and activates the reed switch 194 once each revolution ofhousing 182 to produce switching pulses 80 as illustrated in FIG. 3b..Therefore, in this embodiment, the sinusoidal signal V represents thedirection of the earths magnetic field, and the switching pulses 80represent the direction in which vehicle 196 is heading. The only basicdifference is that the base of the transducer is now fixed to a vehiclerather than to a wind vane. Consequently, the phase of the switchingpulse 80 relative to the maximum value of the signal V, (for clockwiserotation of the flux rod 190), gives the magnetic heading or azimuth ofthe direction in which the front of the vehicle is pointed.

It is obvious that the transducer illustrated in FIG. 14 can be fixed toany vehicle, such as an automobile, tank, or boat, and that the headingof such a vehicle can be easily determined by comparing the phase of themagnetic reed switching pulses with the V,, wave form.

This electronic compass has advantages over the standard magnetic needlecompass which cannot follow quick changes in direction of the vehicle.With the present invention, if the vehicle is subject to sudden andfrequent changes in direction, the speed of motor 180 is merelyincreased until the rotational speed of the flux rod 190 is highrelative to the frequency of changes in direction.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined in the following claims:

1. A transducer-for simultaneously providing signals indicative of thespeed and magnetic azimuth of the flow of a fluid comprising:

a. a housing, fixed to the earth s surface;

b. fluid speed sensing means rotatably mounted on said housing in thepath of said fluid and adapted to rotate in a predetermined direction ata speed proportional to the speed of the flowing fluid;

c. magnetic flux concentrating means fixed to said speed sensing meansfor rotation in the earths magnetic field;

d. magneto-electric transducer means fixed to said housing andresponsive to the magnetic flux in said flux concentrating means forproducing a sinusoidal electric signal having a frequency proportionalto the rotational speed of said speed sensing means and magnitude andpolarity proportional to the magnitude and direction of the earthsmagnetic flux in said flux concentrating means;

e. fluid flow direction sensing means on said transducer for producing,during each revolution of said speed sensing .means, a fluid flowdirection signal each time a predetermined point on said speed sensingmeans has an angular position corresponding to the direction from whichthe fluid is flowing, whereby the phase of said direction signalrelative to said sinusoidal signal indicates the magnetic azimuth of thedirection of fluid flow, and the frequency of said sinusoidal signalindicates the speed of said fluid flow; and

f. said fluid flow direction sensing means comprising a fluidpressure-sensitive electric transducer means for providing saiddirection signal. A transducer as defined in claim 1 wherein a. saidfluid pressure sensitive electric transducer means comprises apressure-sensitive transistor fixed to said housing, and

b. said speed sensing means has a hole therein at said predeterminedpoint to permit fluid pressure to be applied to said transistor, wherebymaximum fluid pressure on said transistor produces said directionsignal.

3. A transducer for simultaneously providing signals indicative of thespeed and magnetic azimuth of the flow of a fluid comprising:

a. a housing, fixed to the earths surface;

b. fluid speed sensing means rotatably mounted on said housing in thepath of said fluid and adapted to rotate in a predetermined direction ata speed proportional to the speed of the flowing fluid;

c. magnetic flux concentrating means fixed to said speed sensing meansfor rotation in the earths magnetic field; d. magneto-electrictransducer means fixed to said housing and responsive to the magneticflux in said flux concentrating means for producing a sinusoidalelectric signal having a frequency proportional to the rotational speedof said speed sensing means and a magnitude and polarity proportional tothe magnitude and direction of the earths magnetic'flux in said fluxconcentrating means; e. fluid flow direction sensing means on saidtransducer for producing, during each revolution of said speed sensingmeans, a fluid flow direction signal each time a predetermined point onsaid speed sensing means has an angular position corresponding to thedirection from which the fluid is flowing, whereby the phase of saiddirection signal relative to said sinusoidal signal indicates themagnetic azimuth of the direction of fluid flow, and the frequency ofsaid sinusoidal signal indicates the speed of said fluid flow, saidfluid being wind; f. said speed sensing means comprising an anemometerhaving a plurality of wind cups each attached to said housing via aradial arm lying in a plane generally parallel to the earths surface; g.said flux concentrating means comprising a magnetic flux concentratingrod mounted in one of said arms; h. said fluid flow direction sensingmeans comprising: 1. a self-heated thermistor mounted on saidanomometer, said thermistor having a maximum resistance when movingdirectly into the wind, due to the cooling effect of the wind; and

2. means for heating the thermistor above ambient temperature and meansfor connecting said thermistor in a circuit for producing said directionsignal corresponding to said maximum resistance of said thermistor.

4. A transducer for providing a signal indicative of a fluid flow speedand direction relative to the known azimuth of one of the earthsmagnetic poles comprisa. a housing, fixed to the earth s surface;

b. fluid speed sensing means rotatably mounted on said housing in thepath of said fluid and adapted to rotate in a predetermined direction ata speed proportional to the speed of the flowing fluid;

c. switch means fixed to said housing at a point having first angularposition corresponding to said known azimuth of said one of the earthsmagnetic poles;

switch activating means fixed to said speed sensing means for activatingsaid switch means once each revolution of said speed sensing means toproduce a first signal indicative of the azimuth of said one magneticpole;

e. fluid flow direction sensing means on said transducer for producing,during each revolution of said speed sensing means, a fluid flowdirection signal each time said direction sensing means passes throughsecond angular position corresponding to the direction from which saidfluid is flowing, whereby the phase of said direction signal relative tosaid first signal indicates the magnetic azimuth of the direction offluid flow, and the frequency of either of said signals indicates thespeed of said fluid flow; and

f. said fluid flow direction sensing means comprising a fluidpressure-sensitive electric transducer for 6. A transducer for producingan electric signal indicative of the direction of one of the earthsmagnetic poles comprising:

producing said direction signal. 5. A transducer for providing a signalindicative of a fluid flow speed and direction relative to the knownazimuth of one of the earths magnetic poles compristo a. a base member;ing: b. a magnetic flux concentrating rod mounted for a. a housing,fixed to the earths surface; rotation relative to said basemember andextendb. fluid speed sensing means rotatably mounted on ing in adirection generally horizontal to the said housing in the path of saidfluid and adapted earths surface, to rotate in a predetermined directionat a speed 15 c. means for rotating said rod in a plane substantiallyproportional to the speed of the flowing fluid; parallel to the earth ssurface;

. switch means fixed to said housing at a point havd. magnetic fieldresponsive transducer means fixed ing first angular positioncorresponding to said to said base and positioned to receive thecomknown azimuth of said one of the earths magnetic ponent of the earthsmagnetic flux passing poles; through said rod to produce sinusoidalsinusiodal switch activating means fixed to said speed sensing electricsignal with a polarity and magnitude inmeans for activating said switchmeans once each dicative of the direction and magnitude of therevolution of said speed sensing means to produce magnetic flux in saidrod;

a first signal indicative of the azimuth of said one e. means forproducing a reference electric signal magnetic pole; each time said rodpasses through a predetermined fluid flow direction sensing means onsaid transangular ositionjn each reyolution whereby the ducer forproducing, during each revolution of Phase 0 f h e e e reiahYe Sald saidSpeed sensing means, a fluid flow direction reference signal isindicative of the dIICCtIOII Of Signal each time Said direction sensingmeans said magnetic pole relative to said reference point; passesthrough second angular position corand responding to the direction fromwhich said fluid is wherem saldhwtor ah ahefhometer dnveh by theflowing, whereby the phase of said direction signal i h h angular posmoheorrespehds to h relative to said first signal indicates the magneticwmd .dlreehohi whereby the frequency of said azimuth of the direction offluid flow and the electric signal is indicative of the speed of thewind frequency of either of said signals indicates the dm'mg e manometerand e Phase of Said Speed ofsaid fluid flow; reference signalrelat lveto a maximum value of said fluid being wind, and said fluid flowdirection i slhuseldal slghal meleauve of the magnet:

sensing means comprising a self-heating thermistor az'muth of the wmdd1reehhmounted on said speed sensing means and exposed Disclaimer3,713,336.The00l0re Bernstein and Joseph G. Miller, Madison, Wis. COM-BINATION FLUID FLOW SPEED AND DIRECTION TRANS- DUCER. Patent dated Jan.30, 1973. Disclaimer filed Mar. 7, 1975, by the inventors. Hereby enterthis disclaimer to claim 6 of said patent.

[Ofiicz'al Gazette July 22, 1.975.]

1. A transducer for simultaneously providing signals indicative of thespeed and magnetic azimuth of the flow of a fluid comprising: a. ahousing, fixed to the earth''s surface; b. fluid speed sensing meansrotatably mounted on said housing in the path of said fluid and adaptedto rotate in a predetermined direction at a speed proportional to thespeed of the flowing fluid; c. magnetic flux concentrating means fixedto said speed sensing means for rotation in the earth''s magnetic field;d. magneto-electric transducer means fixed to said housing andresponsive to the magnetic flux in said flux concentrating means forproducing a sinusoidal electric signal having a frequency proportionalto the rotational speed of said speed sensing means and magnitude andpolarity proportional to the magnitude and direction of the earth''smagnetic flux in said flux concentrating means; e. fluid flow directionsensing means on said transducer for producing, during each revolutionof said speed sensing means, a fluid flow direction signal each time apredetermined point on said speed sensing means has an angular positioncorresponding to the direction from which the fluid is flowing, wherebythe phase of said direction signal relative to said sinusoidal signalindicates the magnetic azimuth of the direction of fluid flow, and thefrequency of said sinusoidal signal indicates the speed of said fluidflow; and f. said fluid flow direction sensing means comprising a fluidpressure-sensitive electric transducer means for providing saiddirection signal.
 1. A transducer for simultaneously providing signalsindicative of the speed and magnetic azimuth of the flow of a fluidcomprising: a. a housing, fixed to the earth''s surface; b. fluid speedsensing means rotatably mounted on said housing in the path of saidfluid and adapted to rotate in a predetermined direction at a speedproportional to the speed of the flowing fluid; c. magnetic fluxconcentrating means fixed to said speed sensing means for rotation inthe earth''s magnetic field; d. magneto-electric transducer means fixedto said housing and responsive to the magnetic flux in said fluxconcentrating means for producing a sinusoidal electric signal having afrequency proportional to the rotational speed of said speed sensingmeans and magnitude and polarity proportional to the magnitude anddirection of the earth''s magnetic flux in said flux concentratingmeans; e. fluid flow direction sensing means on said transducer forproducing, during each revolution of said speed sensing means, a fluidflow direction signal each time a predetermined point on said speedsensing means has an angular position corresponding to the directionfrom which the fluid is flowing, whereby the phase of said directionsignal relative to said sinusoidal signal indicates the magnetic azimuthof the direction of fluid flow, and the frequency of said sinusoidalsignal indicates the speed of said fluid flow; and f. said fluid flowdirection sensing means comprising a fluid pressure-sensitive electrictransducer means for providing said direction signal.
 1. a self-heatedthermistor mounted on said anomometer, said thermistor having a maximumresistance when moving directly into the wind, due to the cooling effectof the wind; and
 2. A transducer as defined in claim 1 wherein a. saidfluid pressure sensitive electric transducer means comprises apressure-sensitive transistor fixed to said housing, and b. said speedsensing means has a hole therein at said predetermined point to permitfluid pressure to be applied to said transistor, whereby maximum fluidpressure on said transistor produces said direction signal.
 2. means forheating the thermistor above ambient temperature and means forconnecting said thermistor in a circuit for producing said directionsignal corresponding to said maximum resistance of said thermistor.
 3. Atransducer for simultaneously providing signals indicative of the speedand magnetic azimuth of the flow of a fluid comprising: a. a housing,fixed to the earth''s surface; b. fluid speed sensing means rotatablymounted on said housing in the path of said fluid and adapted to rotatein a predetermined direction at a speed proportional to the speed of theflowing fluid; c. magnetic flux concentrating means fixed to said speedsensing means for rotation in the earth''s magnetic field; d.magneto-electric transducer means fixed to said housing and responsiveto the magnetic flux in said flux concentrating means for producing asinusoidal electric signal having a frequency proportional to therotational speed of said speed sensing means and a magnitude andpoLarity proportional to the magnitude and direction of the earth''smagnetic flux in said flux concentrating means; e. fluid flow directionsensing means on said transducer for producing, during each revolutionof said speed sensing means, a fluid flow direction signal each time apredetermined point on said speed sensing means has an angular positioncorresponding to the direction from which the fluid is flowing, wherebythe phase of said direction signal relative to said sinusoidal signalindicates the magnetic azimuth of the direction of fluid flow, and thefrequency of said sinusoidal signal indicates the speed of said fluidflow, said fluid being wind; f. said speed sensing means comprising ananemometer having a plurality of wind cups each attached to said housingvia a radial arm lying in a plane generally parallel to the earth''ssurface; g. said flux concentrating means comprising a magnetic fluxconcentrating rod mounted in one of said arms; h. said fluid flowdirection sensing means comprising:
 4. A transducer for providing asignal indicative of a fluid flow speed and direction relative to theknown azimuth of one of the earth''s magnetic poles comprising; a. ahousing, fixed to the earth''s surface; b. fluid speed sensing meansrotatably mounted on said housing in the path of said fluid and adaptedto rotate in a predetermined direction at a speed proportional to thespeed of the flowing fluid; c. switch means fixed to said housing at apoint having first angular position corresponding to said known azimuthof said one of the earth''s magnetic poles; d. switch activating meansfixed to said speed sensing means for activating said switch means onceeach revolution of said speed sensing means to produce a first signalindicative of the azimuth of said one magnetic pole; e. fluid flowdirection sensing means on said transducer for producing, during eachrevolution of said speed sensing means, a fluid flow direction signaleach time said direction sensing means passes through second angularposition corresponding to the direction from which said fluid isflowing, whereby the phase of said direction signal relative to saidfirst signal indicates the magnetic azimuth of the direction of fluidflow, and the frequency of either of said signals indicates the speed ofsaid fluid flow; and f. said fluid flow direction sensing meanscomprising a fluid pressure-sensitive electric transducer for producingsaid direction signal.
 5. A transducer for providing a signal indicativeof a fluid flow speed and direction relative to the known azimuth of oneof the earth''s magnetic poles comprising: a. a housing, fixed to theearth''s surface; b. fluid speed sensing means rotatably mounted on saidhousing in the path of said fluid and adapted to rotate in apredetermined direction at a speed proportional to the speed of theflowing fluid; c. switch means fixed to said housing at a point havingfirst angular position corresponding to said known azimuth of said oneof the earth''s magnetic poles; d. switch activating means fixed to saidspeed sensing means for activating said switch means once eachrevolution of said speed sensing means to produce a first signalindicative of the azimuth of said one magnetic pole; e. fluid flowdirection sensing means on said transducer for producing, during eachrevolution of said speed sensing means, a fluid flow direction signaleach time said direction sensing means passes through second angularposition corresponding to the direction from which said fluid isflowing, whereby the phase of said direction signal relative to saidfirst signal indicates the magnetic azimuth of the direction of fluidflow, and the frequency of either of said signals indicates the speed ofsaid fluid flow; f. said fluid being wind, and said fluid flow directionsensing means comprising a self-heating thermistor mounted on said speedsensing means and exposed to said wind, whereby said thermistor has amaximum resistance when it is moving directly into the wind, and meansfor connecting said thermistor in a detecting circuit whereby saidmaximum resistance is detected to produce said direction signal.